ACTG 368 - A three-arm randomized, multicenter double-blind study in subjects experinced in comb. nucleoside therapy with ZDV (d4T) and 3TC and naive to all protease inhibitors. The study is open to those subjects who have completed participation in ACTG 320/GCRC 1164 and to new participants. The study will compare the contributions of nucleoside analog 1592U89 and the non-nucleoside reverse transcriptase inhibitor DMP-266 as a part of a triple combination which combines the two drugs and the protease inhibitor indinavir (IDV).